The proposed research program aims to generate a new type of therapeutic agent for treatment of Clostridium difficile infections. These infections cause severe intestinal disease, leading to 20,000 deaths annually and an estimated annual cost of $4.8 billion in the United States. Infections due to C. difficile are often recurrent and refractory to antibiotic treatment. C. difficile enters the body as a dormant spore via the fecal-oral route and germinates in the intestine to produce vegetative cells. These cells replicate in the host and generate the toxins that cause illness. During infection, many of the vegetative cells develop into spores, resulting in trillions of infectious particles excreted in host feces. Spores are highly resistant to antibiotics and disinfectants, which facilitates relapse and dissemination of disease. Currently, there are few approved treatment options available for C. difficile infections (CDI) and no treatment that combats the infectious potential of spores produced during an infection. Our over-arching goal is to develop agents that act on both growing vegetative cells and the spore form of C. difficile. In preliminary studies, our collaborative team has discovered that a non-traditional type of agent, nylon-3 polymers, can target vegetative cells and inhibit outgrowth from the spore form. The specific objective of the proposed research is to optimize and further develop these activities, with a focus on generating an orally-deliverable therapeutic polymer. Exploration of nylon-3 materials for antimicrobial applications was inspired by the activities of natural host- defense peptides. The polymers are advantageous relative to these peptides in that the polymers are not degraded by proteases (and should therefore survive passage through the stomach), and the polymers are much less expensive to produce relative to peptides. The use of synthetic polymers as C. difficile therapeutics has the potential to decrease the costs of treating debilitating infections and to lower disease transmission.